#include <stdio.h>

#include "hardware/gpio.h"
#include "pico/stdlib.h"
#include "pico/binary_info.h"

const uint PIN_DIGIT_BASE = 18;
const uint PIN_SEGMENT_BASE = 2;

const uint N_DIGITS = 4;

uint8_t digit_states[4] = { 0b11001100, 0b11111111, 0b10101010, 0b00101001 };

void write_digit(uint8_t digit) {
  const uint mask = (0xffffffff << PIN_SEGMENT_BASE) ^ (0xffffffff << PIN_SEGMENT_BASE + 8);
  gpio_put_masked(mask, (~digit & 0xff) << PIN_SEGMENT_BASE);
  gpio_put_masked(mask, digit << PIN_SEGMENT_BASE);
}

int main() {
  bi_decl(bi_program_description("qCLK driver."));

  stdio_init_all();

  for (uint i = PIN_DIGIT_BASE; i < PIN_DIGIT_BASE + N_DIGITS; i++) {
    gpio_init(i);
    gpio_set_dir(i, GPIO_OUT);
    gpio_put(i, 0);
  }
  for (uint i = PIN_SEGMENT_BASE; i < PIN_SEGMENT_BASE + 8; i++) {
    gpio_init(i);
    gpio_set_dir(i, GPIO_OUT);
  }
  write_digit(0);

  while (1) {
    for (uint i = 0; i < N_DIGITS; i++) {
      uint prev = i == 0 ? N_DIGITS - 1 : i - 1;
      gpio_put(PIN_DIGIT_BASE + prev, 0);
      write_digit(digit_states[i]);
      gpio_put(PIN_DIGIT_BASE + i, 1);
      sleep_ms(1);
    }
  }
}